The present disclosure is directed generally to butterfly valves, and more specifically, to actuation of butterfly valves.
Pneumatically actuated butterfly valves require a means for translating the pistons axial motion into rotary motion to rotate the valve disc from open to closed. Typically a link—with bearings at each end—provides the connection between the piston and the crank arm which rotates the shaft for the butterfly disc. Often there are wear issues associated with the bearings at either end of the crank. Also, in high vibration environments like engine bleed systems, a piston torsional mode may be excited which leads to excessive piston ring wear. In such arrangements, the piston has the rotational inertia and the link provides the torsional stiffness.